steering-head-bearing-adjustment-32-001-77-1011r–777

:.( Service-1n fo rmation BMW Motorrad G~bH R 50 / 5 – R 100 RS Munich,July 77 Service Ett/cb Technical Group: Steering 32 001 77( 1011~ For U.S. and Canada only Subject: Adjusting steering head bearings Gentlemen, Our current service instructions call for the two taper roller bearings to be adjusted free from play, but turning easily. This not only implies great sensitivity on the part of the mechanic but also fails to provide values which can be measured objectively. New comparative tests by BMW’s motorcycle development department have confirmed what motorcycle experts have always maintained: – the entire handling characteristics depend to a lar~e extent on correct steering adjustwent. For this reason, we are now quoting friction values for steering f·ork rotation froir. a precisely determined position. These values can be used for comparison of taper roller bearing preload and thus for confirmation that the steering head bearings have been correctly adj~sted. With effect immediately, the friction values are: Front fork with drum brake 2.6 +0.3 Nm (26 ±3 cmkp) (1.9_+0.2 lb.ft) Front fork with disc brake (single or twin disc) 3.5 -+0.2 Nm (35 -+2 cmkp) (2.6 -+0.14 lb.ft) Since these values are useless to you without suitable tools, a test wrench has been specially developed. In conjunction with a normal commercially-available torsion gauge, this will enable you to check and adjust the motorcycle steering. Since many workshops do not yet possess a friction gauge already needed for correct adjustwent of wheel bearings we are offering a friction gauge in cc,njunction with the above test wrench. L_ / •• ; \ ‘ Kennlnis genommen – Pris connaissance – Noted – Tornado nota – Presa conoscenza : Ablage – Archives – File – Arch”::: – 2 – Here are the numbers of these new BMW tools: Test wrench Friction gauge – 3 1 4 7 50 00 2 570 A workshop equipr.,en t advisory service information bulletin will shortly be issued. Measuring procedure: 1. Put the motorcycle on the center stand sc that the front wheel is off the ground. 2. Move the hydraulic steering damper to the ‘O’ position. On /5 motorcycles, slacken the friction darrper or detach the hydraulic steering damper if the machine is so equipped. 3. Insert a stop between the lower fork bridge and the front frame tube, so that the front fork is held at 20° left lock (see Fig. 1). 4. Place the friction tester with test wrench on the cap nut (see Fig. 2) and turn the fork from the position determined above to the right until the front wheel is again pointing straight ahead. The values quoted on the previous page for forks with either drum or disc brakes must be obtained. Warning, Do not test friction values unless the upper fork bridge and cap nut are tightened to the specified torque. Always n•ake sure that wiri.ng· and control cables are routed ccrrectly, sc that they cannot affect the friction readings. 5. If the friction readings obtained are incorrect, adjust bearing preload. ( Your own experience will undoubtedly have confirmed that the c· operating life of the taper roller bearings depends not only on correct adjustff,ent but to a very large extent also on adequate lubrication. In order to provide better protection for the lower bearing against the penetration of water and dirt, machines have for some time been leaving the asserrbly line equipped with a ‘Nilos’ sealing ring Part nuwber 31 42 1 234 509 between the inner bearir,g face and its contact face on the lower fcrk bridge. This prevents splash water from diluting tte grease packing even when the motorcycle is being washed down. However, it is still best tc avoid cleaning motorcycles with a L powerful, high-pressure water hose. ‘ … / ( ( ( ( – 3 – When forks have to be stripped and re-assembled for any reason, we recommend you to take the opportunity of installing the new sealing ring. Yours very sincerely, BMW MOTORRAD GMBH Munich i. V. i. V. I ,’Gonzalez Blank Illustrations overleaf ( ‘ .~~-, i~:)~.